beta 2-Microglobulin in clinical medicine.

The production of beta 2-microglobulin in normal subjects is quite constant, about 0.13 mg/h . kg. The catabolism almost exclusively through renal elimination. The protein readily passes the glomerular membrane; subsequently more than 99.9% of the filtered beta 2-microglobulin is reabsorbed and degraded in the proximal tubules, only about 5 micrograms/h of the protein appearing in the final urine. Proximal tubular dysfunction leads to an increased urinary concentration. The serum level of beta 2-microglobulin is determined by the glomerular filtration rate and the rate of synthesis. Increased production, with raised serum levels, is sometimes observed in malignancy--mainly at an advanced state, in conditions with neoplastic proliferation of lymphoid B-cells or in inflammatory disorders connected with an activation of the lymphopoetic system. In body fluids, other than plasma and urine, the content of beta 2-microglobulin seems to often reflect a local production. In this review a presentation of the current status and usefulness of beta 2-microglobulin measurements in clinical medicine is included.